Diabetes mellitus may be divided into type 1 diabetes mellitus and Type 2 diabetes mellitus. Type 1 diabetes mellitus is an autoimmune disease in which genetic susceptibility and virus infection cause immunological responses in a pancreas, and β-cells are selectively destroyed. Type 2 diabetes mellitus is preceded by insulin resistance, and has been reported to be caused by complicated factors such as obesity, reduction of insulin receptor, reduction of tyrosine kinase activity, reduction of muscle/adipose tissue type transporter in a muscle tissue and an adipose tissue, and intracellular deficiency of insulin receptor substrate-1(IRS-1).
Especially, type 1 diabetes mellitus is known to be one of typical autoimmune diseases, and is a chronic disease in which pancreas β-cells-recognizable auto-activating T cells destroy insulin-producing pancreas β-cells. Humoral and cellular immune responses are mainly related to type 1 diabetes mellitus, and an autoantibody against various islet cell antibodies exists in the plasma of type 1 diabetes mellitus patients. Autoantibodies, against glutamate decarboxylase (GAD65), insulin, and protein tyrosine phosphatase-related islet antibodies 2 (IA-2), are used together with HbA1C and c-peptide quantification, to diagnose type 1 diabetes mellitus. Early diagnosis and exact determination allow medical treatment to be carried out at an early stage, and then is useful in delaying the progress of type 1 diabetes mellitus. Thus, they are clinically important. In the use of an autoantibody diagnosis, anti-GAD65 antibody showed a sensitivity of about 60 to 80%, anti-insulin antibody showed 40 to 60%, and anti-IA-2 antibody showed 30 to 70%. Even when three autoantibodies are combined, only 80 to 90% of type 1 diabetes mellitus can be covered. Accordingly, it has been required to develop a novel autoantibody diagnosis method for early diagnosis of type 1 diabetes mellitus.